Slide resistor with fine adjustment



Dec. 29, 1970 H. EBERwEnN UAL vSLIDE RESISTOR WITH FINE ADJUSTMENT Filed Dec. 18, 1968 3 Sheets-Sheet l i0 77 al 3 Fig.

7 if? @f sa /q /-fz 8 l ,43

ml' 'hh III|| "W7 T:- I Z Il 20 l@ H-wg i0 r' 'IU I 5 l r l Dec. 29, 1970 H, EBERWEIN EVAL plg SLIDE RESISTOR WITH-FINE ADJUSTMENT Filed Dec. 18, 1968 3 Sheets-Sheet 2 www5."

Dec. 29, 1970 H. EBERWEIN ETAL. Bi

SLIDE RESISTOR WITH FINE ADJUSTMENT Filed Dec. 18, 1968 :5 sheets-sheet s Lm@ Hpg Il. Il!

United States Patent O U.S. Cl. 338-122 3 Claims ABSTRACT OF THE DISCLOSURE In a slide resistor being roughly adjustable by slidingly moving an operating button or handle, the provision of a ne adjustment. The operating button being provided in its interior with a rotatable pinion engaging a gear rack connected with the slide resistor. The button `for slidingly adjusting the slide resistor serving simultaneously for turning the pinion.

The invention relates to a slide resistor having, in addition to a rough adjustment by slidingly moving an operating button, a fine adjustment also.

If a slide resistor is to be used as tuning resistance for capacitance diodes of tuning devices, then a means is required for fine adjustment so as to exactly adjust the resistance in addition to its rough adjustment. Such means for fine adjustment are known for rotary resistors in the form of gears. Slide resistors having a separate fine adjustment device for exact tuning are however not known up to this time. True, there are so-called roll resistors in which the adjustment is carried out by a serrated wheel which is rigidly connected with a pinion rolling on a gear rack and carrying a central contact pin. This arrangement has however the drawback that the total adjustment range of the resistor requires a large number of rotations of the operation wheel for sufficient fine adjustment.

A object of the invention is the provision of a slide resistor offering a fine adjustment at any position of the slide resistor in addition to the rough adjustment by sliding movement of the operating button.

This object is achieved, in accordance with the present invention, by equipping the operating button centrally in its interior 4with a rotatable pinion provided with an operating means, the pinion engaging or being engageable with gear rack attached to the resistor.

According to a further embodiment of the invention, the operating means of the pinion may be supplied by the operating button itself.

In a still further embodiment of the invention, the pinion is held either by a snap-in device in its position of rest or in its position of engagement with the gear rack.

The aforesaid and further objects, features and advantages of the invention will be explained in the following, reference being had to the drawings showing three embodiments as examples on enlarged scales.

In the drawings:

FIG. l is a fragmentary, partly sectionalized side view of the slide resistor and its operating button;

FIG. 2 shows a cross section along line 2-2 of FIG. l;

FIG. 3 is a view similar to FIG. 1 but of another embodiment of the invention;

FIG. 4 shows a cross section along line 4-4 of FIG'. 3;

FIG. 5 is a view similar to FIGS. 1 and 3 but of a still further embodiment; and

FIG. 6 shows a cross section along line 6-6 of FIG. S.

The slide resistor shown in FIGS. 1 and 2 comprises a 3,55 1,871 Patented Dec. 29, 1970 ICC housing 1 in the interior of which are secured a resistance bar 1a and a bus bar 1b. These bars are arranged opposite each other and provided with terminals 1a and 1b. Longitudinally slidably supported in housing 1 is a slide 2 carrying a wiper spring 2a. The wiper spring 2a contacts by its opposite ends the bars la and 1b, respectively. A gear rack 3 is formed on housing 1 and extends in a 1ongitudinal direction of the latter. Slide 2 is provided with two extensions 5 serving for the reception of an operating button 4. Projections or noses 6 on button 4 engage recesses 7 formed near the upper ends of extensions 5 and thereby hold button 4 in its position. A pinion 8 is centrally located in the interior of the operating button 4 and has a frusto-conical part 9 merging into head 10. Head 10 extends through a central opening in button 4. A compression spring 13 is received in a cavity 12 of pinion 8 and biases pinion 8 so as to hold it out of engagement with gear rack 3. So as to operate the ne adjustment at any position of slide 2 along the resistor housing 1, button 10 is pushed down in bringing pinion 8 into engagement with rack 3, whereupon it is rotated so as to finely adjust the position 2 by the coaction of pinion 8 with rack 3.

In FIGS. 3 and 4, the parts corresponding to those of FIGS. 1 and 2 are provided with the same reference numerals; hence, in the following the differences only of the embodiment shown in FIGS. 3 and 4 over the embodiment shown in FIGS. l and 2 will be described. In this embodiment, pinion 8 is formed in one piece with a stem 9a and the combined roughand tine-adjustment button 01 handle 10a. Stem 9a is received in the bore 14 of a bushing 15 which rests on a collar 16 of stem 9a. A compression spring 13a is inserted between the upper end of sleeve 15 and button 10a. Sleeve 15 has an outwardly projecting collar 6a at its upper end which engages the recess 7 of the extension 5 of slide 2. For iine adjustment, button 10a is pushed downwardly in overcoming the force of spring 13 so as to bring pinion 8 into engagement with rack 3. Rack 3 is formed as a separate element inserted into and rigidly connected with the upper wall of resistor housing 1.

The embodiment illustrated in FIGS. 5 and 6 differs from the embodiment shown in FIGS. 3 and 4 merely in the substitution of spring 13a by a U-shaped spring 18 which is held in opposite grooves 19 of bushing 15a and the arms of which are adapted to snap into circumferential grooves 17 of stern 9a. Upon engagement of spring 18 in the lower one of grooves 17, the pinion 8 is kept out of engagement with rack 3 whereas upon engagement between spring 18 and the upper one of grooves 17, pinion 8 is held in engagement with rack 3 so as to permit fine adjustment of the resistor by rotation of knob 10a. This permanent engagement between pinion 8 and rack 3 is believed to be sometimes preferable to the engagement requiring for fine adjustment the maintenance of a pressure overcoming the force of spring 13 or 13a, respectively, of the embodiments shown in FIGS. 1, 2 and 3, 4, respectively.

While there have been described what at present are believed to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is aimed, therefore, to cover in the appended claims all such changes and modications as fall within the true spirit and scope of the invention.

What is claimed is:

1. In a slide resistor, an elongated housing, a first button connected with a slide mounted within the housing and adapted to be moved in the longitudinal direction of the housing, a contacting wiper carried by said slide conductingly bridging the space between a bus bar and an elongated resistor element, said bar and said resistor element being mounted within the housing and extending in the longitudinal direction of the slide movement, a gear rack rigidly connected with said elongated housing and extending parallel to said bus bar and said resistor element, a second button positioned within said rst button and extending to the outside thereof, said second button being rigidly connected with a pinion, said pinion being movable transversely of the said longitudinal direction of movement of said slide to thereby alternately engage and become disengaged from said gear rack, resilient means inserted between said second button and said slide and resiliently holding said second button in the position of disengagement with said rack.

2. The slide resistor according to claim 1 having compression spring means inserted between said second button and said slide, said spring means being adapted to hold said pinion normally out of engagement with said rack and permitting it to be brought into engagement with said rack in overcoming the force exerted by said sprmg means.

References Cited UNITED STATES PATENTS 2,091,371 8/1937 McMaster 338--181 2,242,327 5/1941 Rubinstein 338-183 3,307,133 2/1967 WOUT 338--183X 3,465,277 9/1969 Bang 338-183 LEWIS H. MYERS, Primary Examiner G. P. TOLIN, Assistant Examiner U.S. Cl. X.R. 338-181, 183 

